This invention relates to a magnetic disk apparatus, a magnetic disk used for the magnetic disk apparatus, a particles coating apparatus, and a method of forming concave or convex portions on the magnetic disk.
The magnetic disk apparatus records/regenerates information using its magnetic head, which flies and moves above a turning magnetic disk.
Usually, the magnetic head uses the contact start stop system (hereafter, to be referred to as CSS). The magnetic head comes in contact with (lands on) an area on the object magnetic disk while the disk is stopped and it flies with the turning of the disk for recording/regenerating information.
In this case, if the area on the surface of the magnetic disk to be contacted by the magnetic head (hereafter, to be referred to as a CSS area) is smooth, the magnetic head is absorbed by the magnetic disk when it flies/lands from/on the surface of the disk to apply an impact force to the disk. If some water exists between the magnetic head and the magnetic disk when the disk stops (the head lands), the magnetic head has a tendency to stick fast to the magnetic disk. In the worst case, information recorded on the disk is damaged.
To solve such a problem, for example, a method of forming many bumps having no sharp angles in the CSS area was disclosed in Japanese Patent No. 307748/1993 (hereafter, to be referred to as the prior art).
The prior art describes that many bumps having no sharp angles are formed in the CSS area at pitches of 1 .mu.m or under, so that the magnetic head is prevented from sticking fast to the magnetic disk, and this improves the durability of the magnetic disk accordingly. However, the prior art only describes that the bumps have no sharp angles and does not indicate the sizes of those bumps.
When a magnetic disk having many bumps was turned in practice, it was found that the ability to prevent the magnetic disk from sticking fast to the magnetic head depended on the size of those bumps. Furthermore, the magnetic head became unstable in floating and was not effective for improving the recording density of information.
Additionally, although the prior art describes how to form bumps for a magnetic disk whose base is made of plastic, it does not describe any method of forming bumps for other magnetic disks, whose bases are made of aluminum and glass. Thus, it has been impossible so far to apply the prior art to those magnetic disks whose bases are made of aluminum and glass.
An object of this invention, therefore, is to provide a magnetic disk apparatus which is excellent in reliability and durability and which enables high density recording, as well as a magnetic disk to be used for such a magnetic disk apparatus.
Another object of this invention is to provide a particles coating apparatus which is excellent in reliability and durability and which may be used for forming concave or convex portions on a magnetic disk which is capable of high density recording, and a method of forming such concave or convex portions on the magnetic disk.